Spark-plug.



1. J. SMITH, In.

SPARK PLUG.

APPLICATION FLED NOV. 13, 1915.

Patented 001;. 10, 1916.

A TTOHNEYS UNITED sTATEs PATENT oEEIoE.

JOSEPH JY'OHII'I'SHITH, JB.; 0F BENTON HARBOR, MICHIGAN.

i SPARK-PLUG.

Speoication of Letters Patent.

Patented Oct. 10, 1916.

Application med November 1s, 1915. serial No. 61,324.

M invention relates to improvements in spar plugs, and it consists in the combination, construction and arrangement herein described and claimed.

An object of In invention is to provide a spark plug having a porcelain core, the parts being so arranged that the core may expand and contract without injuries.

A further object of my invention is to provide a spark plug having means for intensifying the spark.

A further object of my invention is to provide a spark plug havin a central glass tube around which is molded a porcelain insulator, said glass tube containing a central conducting member, the conducting member, glass tube and porcelain insulator being made air and gas-tight.

A further object of my invention is to provide a spark plug of the type described which is cheap to manufacture, but strong and durable.

Other objects and advantages will appear in the following specification, and the novel features of the Invention will be particularly pointed out in the appended claims.

My invention is illustrated in the accompanying drawing, forming part of this application, in which- Figure 1 is' a central section through the device, Fig. 2 is a section on the line 2-2 of Fig. 1, Fig. 3 is a perspective view of a ferrule, Fig. 4 is a sectional view through a modiiied form of core, and Fig. 5 is a section along the line 5-5 ofv Fig. 4.

In carrying out my invention I make use of a sleeve or shell .1, which has a threaded portion 2 arranged to enter the opening 3 in the cylinder 4. rIhe sleeve is provided with an inwardly extending ange 5 which forms a shoulder for supporting the core as will be hereinafter explained. The sleeve is threaded internally at 6 to receive a screw plug 7 which' is provided with a central opening- 8. The construction thus far described is ordinary and forms no part of my invention, except in so far as these parts coperate with thenovel features here- I'nafter pointed out.

In forming the core ofthe plug a glass tube 9 isprovided. In the upper end 1s a conducting terminal 10 which is threaded for a bin ing post 11., In the lower part of the glass tube is secured a terminal 12. Secured to the upper terminal and extending downwardly to the lower terminal 12 is a strip of flexible conductin material 14. A porcelain body portion 15 1s now molded around the glass portion 9 and its terminals. This porce ain body portion is provided 4with an enlarged portion 153L arranged to enter between the flange 5 and the end of the plug 7. Between the portion 15aand the "plug 7 I s disposed a gasket 16. A ferrule 17 whlch 1s made of metal fits on the lower portion of the porcelain, and has a flange 17 a: With the parts made as shown in Fig. 1, 1t will be seen that by screwing the plug 7 lirmly down on the gasket 16 the core is held securely. The ferrule -17 serves a double function; its flange 17a serves as a gasket, while the lower portion serves as a means for retaining any portions of the porcelain core which may crack oif. It will be observed that the porcelain has opportunities to expand or contract freely in all directions with the exception of the point at which it is held, to-wit: at the henlarged portion 15, or rather on the 'upper and lower sides of the enlarged portion. Any expansion upwardly or downwardly, of course, will make the joints tighter and thereby prevent the escape of gases.

In Figs. 4 and 5 I have shown a modified I form of the device. In constructing this modified form I provide an inner tube 9 of glass, at the top of which is a threaded terminal 10 and at the bottom is a terminal 12. Disposed in the glass tube at equal intervals are conducting members 14 which are separated by gaps 14. After the terminals and the conducting members 14 have been put in place, the glass tube is comressed so as to hold these members securely 1n osition, as shown in Fig. 5. A porcelain bo y portion 15 is then molded around the glass tube with its inclosed conducting portions. This body portion is provided with an extension 15a and with a window opening 20, this window opening being opposite one of the spark gaps 14. ,In this form of the invention the inner conducting portions which forms `the subject of this invention` is that th'ere is no danger of any of the parts working loose, since the core portions are molded ,together in the manner described. The porcelain core has a smooth appearance and is of durable construction.

1. .In a spark plug construction, a core v comprising a central tube of glass having terminals held at the opposite ends of the tube, a conducting portion disposed between the terminals inside the tube, and an insulating body portion molded \around said central glass portion and said terminals.

2. In a spark plug construction, a core comprising a central tube of glass having terminals held at the opposite ends of the tube, a conducting portion disposed between the terminals inside the tube, an insulating body portion molded around said central glass portion and said terminals, said insulating body portion having a laterally extending portion, a metallic sleeve or shell having an inwardly extendin ange, a screw plug, said laterally exten ing portion being arranged to extend between said annular flange and said screw plug.

3. In a spark plug construction, a core comprising a centralztube of glass having terminals held at the opposite ends of the tube, a conducting portion disposed between the terminals inside the tube, an insulating body portion molded around said central glass portion and said terminals, said, insulating body portion having a laterally ex` tending portion, a metallic sleeve or shell hnaving an inwardly extending -lange, a screw plug, said laterally extending portion lbeing arranged to extend between said anynular Hange and said screw plug, and a metal ferrule having a flange disposed between said. laterally extending portion and said annular flange, the lower part of said ferrule inclosing a portion 'of thcvsfporcelain insulator.

4. In a spark plug construction, apcore comprising a central tube of glass having tending portion, a metallic sleeve or shell having an inwardly extending Harige, a screw plug, said laterally extending portion being arranged to extend between said annular flange and said screw plug, a metal ferrule having a flange disposed between said laterally extending portion and said annular ange, the lower part of said ferrule inclosing a portion of the porcelain insulator, and a gasket disposed on the oppo; site side of the extension from the ferrule flange and arranged to be engaged by said screw plug for clamping the parts together.

5. In a spark plug construction, a central glass tube, a plurality of conducting members disposed within the glass tube and heldtherein by frictional engagement with the glass tube, said oonductingmembers being spaced apart, a conducting terminal at each end of said glass tube, and a porcelain insulating body portion inclosing said glass tube and a portion of each of said terminals.

6. In a spark plug construction, a central glass tube, ,a plurality of conducting members disposed within the glass tube and held therein by frictionalvengagement with the glass tube, said conducting members being spaced apart, a conducting terminal at each end of said glass tube, and a porcelain in` sulating body portion inclosing said glass tube and a portion of each of said terminals, said porcelain body portion being provided with an opening on one side arranged to register with one of the gaps between adjacent kconducting members within the central glass tube.

JOSEPH JOHN SMITH, JR. Witnesses: g

WILLIAM S. KIN'sELY, WILLIAM P. HOLDER. 

